Quantification of serum and cerebrospinal fluid gelsolin in familial amyloidosis, Finnish type (AGel)

Abstract

Familial amyloidosis, Finnish type (FAF) or AGel is an autosomal dominant systemic amyloidosis, characteristic symptoms of which are progressive polyneuropathy and corneal lattice dystrophy. The amyloid in FAF patients consists of peptides of an actin modulating protein, gelsolin, with the substitution ofAsn or of Tyr for Asp₁₈₇. We developed a novel competitive radioimmunoassay for gelsolin quantification in serum and CSF The serum gelsolin concentration in our patient material was significantly higher (248 μg/ml) than in the controls (179 μg/ ml) (P=0.0012). The serum gelsolin levels inpatients correlated with age (P=0.0001), whereas no age-dependency was observed in the control group. The mean CSF gelsolin concentration in patients below the age of 50 was lower (7.1 μg/ml) than in controls (10.8 μg/ml), but increased with age in the patient group (P=0.014), as did the total CSF protein (P=0.015). Immunoblotting with antibodies to gelsolin revealed one extra fragment of 60 IcDA in the serum and two extra fragments of 60–85 kDa in the CSF of the patients. These findings suggest that the metabolism of gelsolin is altered in FAF The novel RIA method presented here can serve as a valuable tool in future analyses aimed at monitoring the gelsolin level in vitro or in vivo.

Key Words:

• Amyloidosis
• Familial
• Finnish
• Polyneuropathy
• Corneal Lattice Dystrophy
• Gelsolin